Device for the temperature-compensated optical detection of an oxygen content of a fluid

ABSTRACT

A sensor arrangement includes a reaction subassembly having a housing and a detector subassembly. The housing is a layered component arrangement encompassing a luminophore-containing reaction laminate excitable, by irradiation with a first electromagnetic radiation of a first wavelength, to emit a second electromagnetic radiation of a second wavelength different from the first wavelength; and a temperature-detection laminate emitting an infrared radiation. The housing includes an opening for introducing a fluid, a reaction window and a temperature-sensing window. The reaction window transmits the first and second electromagnetic radiation, and the temperature-sensing window is penetrable by infrared radiation. The detector subassembly encompasses a radiation source emitting the first electromagnetic radiation, a radiation detector detecting the second electromagnetic radiation, and an infrared detector detecting, through the temperature detection window, the infrared radiation emitted from the temperature detection laminate. The reaction laminate and the temperature-detection laminate are embodied separately.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 16/493,381, filed Sep. 12, 2019, which is the National Stage ofInternational Application No. PCT/EP2018/055497, filed on Mar. 6, 2018,which claims the benefit of German Application No. 10 2017 204 082.3,filed on Mar. 13, 2017. The entire contents of each of which are herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a planar layered component arrangementfor temperature-compensated optical detection of an oxygen content of afluid, the planar layered component arrangement encompassing:

-   -   a luminophore-containing reaction laminate whose luminophore is        excitable, by irradiation with a first electromagnetic radiation        of a first wavelength, to emit a second electromagnetic        radiation of a second wavelength different from the first        wavelength, the excited emission behavior of the luminophore        being dependent on an oxygen partial pressure in a fluid        contacting the luminophore; and    -   a temperature-detection laminate emitting an infrared radiation.

A layered component arrangement of the species is known from US2013/0023782 A1. This document describes a sensor arrangement having alayered component arrangement of this kind for measuring an oxygenconcentration of a respiratory gas based on the measurement principle,known per se, of oxygen-induced luminescence quenching of luminophores.In this context, luminophores present in the reaction laminate areexcited, by irradiation with the first electromagnetic radiation, toemit an electromagnetic radiation that is different from the first. As arule, the second electromagnetic radiation has a longer wavelength thanthe first electromagnetic radiation.

The underlying measurement principle can be presented in simplifiedsummary fashion as follows: An energy input into the luminophore takesplace as a result of irradiation with the first electromagneticradiation. The excitation energy imparted to the luminophore byirradiation is delivered back, with a certain time offset, in the formof the second electromagnetic radiation. If the luminophore excited byirradiation with the first electromagnetic radiation is in contact withoxygen, however, a radiation-free deexcitation of the luminophore takesplace by energy transfer to the contacting oxygen. Oxygen present at theluminophore thereby influences the latter's emission behavior inresponse to the excitation produced by irradiation.

The oxygen that contacts the luminophore influences the latter'semission behavior when excitation is otherwise identical in terms of theintensity of the second electromagnetic radiation, and in terms of theemission duration of the second electromagnetic radiation. It isconsidered more accurate to evaluate the emission behavior of theluminophore, as a response to irradiation with the first electromagneticradiation and influenced by the presence of oxygen, based on the timecharacteristic of the emission behavior, compared with evaluation basedon the intensity that is influenced, since in contrast to an evaluationbased on intensity, an evaluation based on the time characteristic ofthe emission of the second electromagnetic radiation is uninfluenced, orat least less influenced, by age-related bleaching of the luminophore.

The emission behavior of luminophores is furthermore influenced, underotherwise identical conditions, by the temperature of the luminophore.This complicates the evaluation of the (usually sensorially observed)emission behavior in a variable temperature environment. Avariable-temperature environment exists, for example, when measuring theoxygen concentration in a respiratory gas, which as a rule is deliveredto the patient at a different temperature than when he or she exhales itagain after a certain degree of metabolization. The temperature of theexhaled respiratory gas can also change depending on the patient's stateof health.

To solve this problem, US 2013/0023782 A1 proposes to measure thetemperature of the luminophore-containing reaction laminate innoncontact fashion using an infrared detector. The intention is todetect the temperature of the luminophore simultaneously with detectionof its emission behavior, so that the emission behavior can be correctlyevaluated with a knowledge of the temperature.

In accordance with US 2013/0023782 A1, the luminophore-containingreaction laminate and the temperature-detection laminate are thereforeone and the same body.

A planar layered component arrangement for a sensor arrangement formeasuring an oxygen content of respiratory gas is furthermore known fromU.S. Pat. No. 7,833,480 B2. The teaching of this document as well is toeliminate the system-inherent uncertainty in the evaluation of thedetected emission behavior which results from the temperature dependenceof the emission behavior of luminophores by using a heating device tobring the reaction laminate to a constant known temperature and maintainit there. The temperature of the luminophore thus does not change duringdetection, and the emission signal that is obtained can be evaluated.

The approach just recited is disadvantageous because of its considerableinstrumental complexity, since it is necessary to provide on the layeredcomponent arrangement a heating device that must be supplied withenergy. The additional heating device can furthermore distort themeasurement result or can fail to eliminate the temperature dependenceto the desired extent, since because of the measurement principle it isnecessary for the excited luminophore to come into contact with oxygen.A certain degree of convective heat transfer between the reactionlaminate and the measured-object fluid whose oxygen content is to bedetected is thus unavoidable, so that even though a heating device isprovided, the temperature of the luminophore during detection of itsemission is not necessarily accurately known.

The approach proposed by the document US 2013/0023782 A1 of the species,for detecting the temperature of the reaction laminate and fordata-based temperature compensation of the detected emission behavior,is likewise not without its disadvantages.

For one, with the approach according to the species two radiationsources and two radiation detectors are present in the same measurementspace. The first radiation source is intended to excite the luminophorein the reaction laminate by emitting the first electromagneticradiation. This excitation usually does not occur in the infraredwavelength region of electromagnetic radiation, but it is not to beruled out that this first radiation source might also radiate, alongwith the desired first electromagnetic radiation, further wavelengthsthat extend into the infrared and thus might constitute an interferencesignal source.

The second radiation source is the luminophore of the reaction laminate,which emits both the second electromagnetic radiation in response to itsexcitation, and an infrared radiation corresponding to its temperature.

On the one hand, the wavelengths of the two radiations (secondelectromagnetic radiation and temperature-based infrared radiation) canbe close to one another and can be difficult to distinguish, which inturn constitutes a source of mutual interference between the respectivesignals.

On the other hand, the known reaction laminate is wetted on one of itssides with the measured-object fluid whose oxygen content is to bedetected, and on its opposite side is detected in terms of the radiationproceeding from it. The known reaction laminate must therefore beshielded with respect to both the first radiation source and theradiation detectors, in order to prevent oxygen-containing fluid fromalso traveling from the detection side to the luminophore of thereaction laminate and distorting the detection of the emission behavior.

The at least oxygen-tight shielding of the reaction laminate withrespect to the first radiation source and the detector arrangement mustallow both the second electromagnetic radiation and thetemperature-based infrared radiation to pass with as little impairmentas possible, so that the emission behavior of the reaction laminate canbe detected with minimal distortion. This results in a considerablelimitation in terms of the materials usable for shielding. For somewavelength regions of the second electromagnetic radiation andtemperature-based infrared radiation it may in fact be impossible insome circumstances to find any material that transmits both types ofelectromagnetic radiation in sufficiently undistorted fashion.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to refine a planarlayered component arrangement of the species in such a way that thedisadvantages recited above in connection with the known layeredcomponent arrangement of the species are mitigated or entirelyeliminated. The intention is therefore to furnish a layered componentarrangement that makes possible very accurate optical detection of anoxygen content of a fluid by temperature compensation of the detectedemission behavior of the reaction laminate, while having a physicalstructure that is as simple as possible.

This object is achieved according to the present invention in that thereaction laminate and the temperature-detection laminate are embodiedseparately from one another.

Thanks to the separate embodiment of the reaction laminate andtemperature detection laminate, the two laminates can be providedphysically separately on a fluid-conveying conduit or on afluid-receiving vessel, so that the apparatuses required forinstrumental detection of the radiation proceeding from the twolaminates can be provided physically separately from one another. Theradiation source of the first electromagnetic radiation can thus bearranged in a manner that is physically separate, and is thus shielded,from an infrared detector, since the radiation source only has toirradiate the reaction laminate and the infrared detector only has todetect the temperature-detection laminate. The radiation source of thefirst electromagnetic radiation is thus eliminated as a source ofinterference for noncontact temperature detection by thetemperature-detection laminate.

The reaction laminate and the temperature-detection laminate canfurthermore be arranged in measurement environments that are optimallyadapted to their respective requirements, so that detection of thesecond electromagnetic radiation by the reaction laminate can occuroptimally, as can detection of the infrared radiation by thetemperature-detection laminate.

When a “laminate” is referred to in the present Application, what ismeant thereby is that this layered body, constituting a planar body, hasa substantially greater dimension in two mutually orthogonal spatialdirections than in its thickness direction respectively orthogonal tothe two aforesaid spatial directions. The thickness direction istherefore always the shortest dimension of the laminate.

In principle, it can be sufficient for the reaction laminate and/or thetemperature detection laminate to comprise only a single layer. Each ofthe laminates can, however, comprise a plurality of layers if that isnecessary or useful for the function or intended purpose thereof.

One problem with constituting the reaction laminate andtemperature-detection laminate separately involves assessing theinformative value of the temperature detected at thetemperature-detection laminate with regard to the actual temperature ofthe reaction laminate. A maximally simple solution to this can involveusing an identical copy of the reaction laminate as atemperature-detection laminate, and detecting only the secondelectromagnetic radiation at one of the two laminates and only theinfrared radiation at the respective other laminate.

Although this is a possible embodiment of the present invention, on theone hand the use of a further reaction laminate as atemperature-detection laminate is expensive and therefore economicallyquestionable. On the other hand, without a guarantee of an actuallyidentical configuration of the two reaction laminates, and withoutarrangement thereof under maximally identical operating conditionsduring detection of the radiation proceeding from them, a calibration isnevertheless necessary in order to allow a sufficiently accurateinference, from the infrared radiation detected at thetemperature-detection laminate, as to the actual temperature of thereaction laminate. Lastly, the second electromagnetic radiation that canbe excited at the luminophore can interfere with the infrared radiationof the temperature-detection laminate.

It is therefore preferred, in the interest of a maximally simple andeconomical design for the planar layered component arrangement accordingto the present invention, if the temperature-detection laminate isdevoid of luminophore.

This ensures that a luminophore at the temperature-detection laminate isnot inadvertently excited to emit electromagnetic radiation that mightinterfere with detection of the infrared radiation proceeding intemperature-related fashion therefrom. Because optimally reliableconversion of the temperature, ascertained by infrared radiationdetection, of the temperature-detection laminate into a temperature(assumed or determined on the basis thereof) of the reaction laminatecan or should be accomplished in any case by means of a data processingapparatus on the basis of a previously performed calibration, thephysical configuration of the temperature detection laminate can beconsiderably simplified as compared with that of the reaction laminate.Provision can therefore be made, very generally, that the reactionlaminate has, at least in portions, a layer structure that differs interms of layer material and/or layer sequence and/or layer thicknessfrom that of the temperature detection laminate.

Provision can be made, for example, that the two laminates (reactionlaminate and temperature-detection laminate) comprise a uniformsubstrate ply on which different functional layers are applied, forexample in one case at least one luminophore containing layer and inanother case a layer intended for temperature detection by detection ofinfrared radiation; or the substrate ply itself serves on thetemperature detection laminate directly, without a further additionalfunctional layer, for the detection of infrared radiation and thus fortemperature detection. It is then possible, because of the presence of acommon layer, to embody the reaction laminate and thetemperature-detection laminate as an integrally continuous laminate. Thelayered component arrangement can then be a one-piece layered componentarrangement.

In the interest of optimum functionality of the two laminates, however,it is also conceivable for them to be constructed entirely differently,and to have completely different layer structures with regard to atleast one of the aforementioned layer parameters.

In the interest of a maximally informative, accurate result fromdetection of the oxygen content in the fluid that is to be detected(measured-object fluid), it is advantageous if detection of theradiation proceeding from the layered component arrangement does notinterfere with the fluid to be detected, and vice versa. According to anadvantageous refinement of the present invention, provision is made forthis purpose that the reaction laminate and the temperature-detectionlaminate each have a fluid-contact side on which the respective laminateis configured for contact with the measured-object fluid, and adetection side, opposite from the fluid contact side, which isconfigured for interaction with radiation detectors.

Noncontact optical sensing of the layered component arrangement underdiscussion here is preferred not only because the absence of contactreduces the risk of interference between the processes being detectedand the very measurement technique being used for that purpose.Contact-based temperature detection of the temperature of the reactionlaminate using measurement sensing elements and the like is alsodifficult or impossible because most measurement sensing elements thatare sufficiently strong and robust detect temperatures (and changes intemperature) too slowly and would thus, in a context of changingtemperatures, indicate a temperature that is not the actual temperatureof the reaction laminate at the point in time at which an emission isdetected.

Temperature sensing elements that can detect temperature changes quicklyenough, conversely, have proven to be too failure-prone and too delicateto be used in a safety-critical sector such as the detection of oxygenconcentrations in a respiratory gas during artificial ventilation.

Since it is consequently important that the temperature-detectionlaminate, if it comprises the aforementioned detection side andfluid-contact side, convey a temperature change on the fluid-contactside as quickly as possible to the detection side, it is advantageous ifthe temperature-detection laminate comprises a layer made of a materialhaving the best possible thermal conductivity, which furthermore can bethin. Concretely, provision can be made for this purpose that thetemperature-detection laminate comprises a metal foil.

The metal foil can in principle be any metal foil, for example a copperfoil, although the latter is susceptible to oxidation specifically in anoxygen-containing environment, and its properties change as oxidationincreases. What is proposed as a metal foil is therefore preferably analuminum foil, which self-passivates and can therefore furnishconsistent material properties over a long period. An aluminum foil,like other metal foils, can furthermore be embodied with sufficientstrength even at a thin film thickness of less than 15 um. A metal foil,in particular the aforesaid aluminum foil, constituting part of thetemperature-detection laminate or constituting said laminate, preferablyhas a thickness in the range from 6 to 12 um, preferably in the rangefrom 8 to 11 um. Thanks to the high thermal conductivity furnished bymetal, in particular aluminum, heat is conducted quickly through thematerial. The thermal path is furthermore short because the materialthickness is thin (less than 15 um), so that a temperature change on thefluid-contact side is detectable within a few milliseconds on thedetection side.

The reaction laminate, on the other hand, can be constructed as a knownreaction laminate and can comprise, for example, a porous substrate ply,permeable to oxygen molecules, made of polyvinylidene fluoride. Anyknown reaction laminates are nevertheless usable in the present case onthe layered component arrangement being discussed here.

In order to provide further assurance that a temperature which changeson the fluid side becomes detectable as quickly as possible on thedetection side of the temperature-detection laminate, provision is madeaccording to a refinement of the invention that an outer surface of themetal foil constitutes the fluid-contact side of thetemperature-detection laminate.

Preferably at least one laminate from among the reaction laminate andtemperature detection laminate is flat. Particularly preferably, bothlaminates are flat, so as to interfere as little as possible with anyflow of the fluid whose oxygen content is to be detected. When the atleast one laminate from among the reaction laminate andtemperature-detection laminate is used to detect the oxygen content of aflowing fluid, the at least one laminate, preferably both laminates, canthen, for minimal interference with the measured-object fluid flow, becurved around an axis of curvature that is parallel to the flowdirection of the fluid at the attachment location of the at least onelaminate. The at least one laminate is preferably curved only aroundthat axis of curvature.

The laminates can be connected to the housing adhesively, for example byway of an adhesive bead that is applied on the detection side of thelayered component arrangement and leaves uncovered a region,respectively provided for radiation detection, of the detection side ofthe respective laminate. Radiation emission from the at least onelaminate, and detection thereof, are thus not interfered with by theadhesive.

Alternatively or additionally, one or both laminates can be connected tothe housing by way of an adhesive tape, the adhesive tape beingadhesively connected in part to the fluid-contact side and in part tothe housing, leaving uncovered a region of the respective fluid-contactsides. Contact between the at least one laminate and the fluid is thusnot impaired by the adhesive tape.

As a general principle, the temperature-detection laminate can comprisea substrate ply that carries a functional layer. This has already beenmentioned above. The substrate ply can be, for example, theaforementioned metal foil, which can be furnished to be sufficientlystable with little thickness. On the detection side, thetemperature-detection laminate can comprise an emission layer, carriedby the substrate ply directly or indirectly (i.e. with interposition offurther layers), having an emissivity of not less than 0.75. Evenbetter, the emission layer has an emissivity of not less than 0.9. Thehigher the emissivity, the more effectively obtrusive reflection at thedetection side of the temperature-detection laminate can be avoided.This provides additional assurance that the temperature-detectionlaminate is in fact the source of the infrared radiation detected in thevicinity of its detection side, and that said radiation has not simplybeen reflected at the surface of the detection side toward thecorresponding detector.

As a general principle, it is not to be ruled out that the emissionlayer and the substrate ply are identical in terms of material, and thatthe emission layer is constituted on the detection side by mechanicaland/or chemical roughening of the surface of the substrate ply on thedetection side. This is appropriate especially with substrate plieshaving a high material-inherent emissivity of more than 0.75.

Because the metal foil which is preferred as a substrate ply will oftenhave undesirably highly reflective surfaces, however, a separateemission layer on the substrate ply can be advantageous. In order toallow maximally advantageous emission behavior in the infraredwavelength region to be obtained, it is advantageous if the emissionlayer contains color pigments. The color of the color pigments playsonly a subordinate role, since many color pigments are “black” in theinfrared wavelength region and thus furnish a sufficiently highemissivity. The use of color pigments that are anthracite-colored orblack is nevertheless preferred.

In experiments, a carbon-containing layer has proven successful. Theemission layer can be applied, for example, as a carbon-containingpaint. For example, a carbon containing conductive paint of Peters GmbH& Co. KG in Kempen (DE), having the designation “SD 2843 HAL,” hasproven to be suitable.

An epoxy can also constitute the emission layer. Epoxies can also beapplied onto the substrate with a thin layer thickness, for exampleusing printing technology or by spraying. They form an advantageouslystrong, robust surface after curing. Possible advantageous epoxies forconstituting an emission layer are obtained from Polytec PT GmbH inWaldbronn (DE) under the product designation EP 601 or EP 653, of USPClass VI. When these epoxies are used they should preferably be filledwith color pigments, once again preferably with black color pigments forthe reasons recited above.

Because the layered component arrangement under discussion here issuitable and intended for direct detection of the oxygen partialpressure of a fluid and, derived therefrom, the oxygen content of thefluid, the present invention also relates to a reaction subassemblyencompassing a housing and a layered component arrangement as describedand refined above which is provided in the housing; the housingcomprising an opening through which a fluid is introducible into thehousing; the housing comprising a reaction window through which thereaction laminate is reachable by the first electromagnetic radiationand which is penetrable by the second electromagnetic radiation; and thehousing comprising a temperature sensing window, arranged physicallyremotely from the reaction window, which is penetrable by the infraredradiation emitted from the temperature-detection laminate.

The measured-object fluid whose oxygen partial pressure is to bedetected is introducible into the housing for detection. With thewindows (reaction window and temperature-detection window) that areembodied separately from one another and physically remotely from oneanother, the electromagnetic radiation proceeding from the respectivelaminates (reaction laminate and temperature-detection laminate) can bedetected at locations located physically remotely from one another, sothat the electromagnetic radiations involved cannot interfere with oneanother.

In order to equip the housing in maximally optimum fashion for detectionof the electromagnetic radiation proceeding on the one hand from thereaction laminate and on the other hand from the temperature-detectionlaminate, the reaction window can be configured physically differentlyfrom the temperature-detection window.

The physically different configuration can be expressed firstly by adifferent selection of material. Alternatively or additionally,provision can be made that the reaction window is thicker than thetemperature-detection window. A zero thickness of thetemperature-detection window is expressly to be included in thiscontext. A sufficiently thick configuration of the reaction window isalso advantageous because the reaction window not only must enablepassage of the first and the second electromagnetic radiation, but alsois intended to shield the reaction laminate on the detection side fromcontact with oxygen that does not derive from the measured object fluid.

A thinner configuration of the temperature-detection window makes itpossible, when a material that is optimally transparent to infraredradiation is not available, at least to make the less-optimum materialsufficiently thin that it presents as little interference as possible.

Selection of a material transparent to infrared radiation can bedispensed with, however, if the solution resorted to is the one alreadyindicated above, namely a temperature-detection window having athickness of zero. Provision is correspondingly made, according to aparticularly preferred refinement of the present invention, that thereaction window comprises a material that is transparent to light in theoptically perceptible wavelength region; and that thetemperature-detection window encompasses a hole that passes through thehousing in its thickness direction and is covered by thetemperature-detection laminate.

Especially when the temperature-detection laminate comprises the metalfilm recited above as preferred, the hole that passes through a housingwall as a temperature detection window can be covered securely andpermanently with the temperature detection laminate. The detection sideof the temperature-detection laminate is then preferably exposed in thehole for any infrared detector arrangement that may be provided.

The hole that passes through the housing and constitutes atemperature-detection window preferably has a cross-sectional hole areathat increases with increasing approach from the housing side facingaway from the temperature-detection laminate toward the housing sidelocated closest to the temperature-detection laminate. The hole ispreferably embodied so as to open negatively conically toward thetemperature-detection laminate, so that it can correspond at leastapproximately to a detection cone of an infrared detector for detectinginfrared radiation proceeding from the temperature-detection laminate.

In order to avoid external interfering influences, the housing surfacedelimiting the hole between the outer side and inner side of the housingcan be coated, in particular mirror-coated. It is thereby possible toprevent a housing made of transparent material from acting as an opticalguide and directing to the temperature detection window electromagneticradiation that does not proceed, as infrared radiation, from thetemperature-detection laminate.

In principle, the housing can be cup-shaped, i.e. embodied with only oneopening through which measured-object fluid can be introduced and thendischarged. A housing of this kind can be used, for example, todetermine an oxygen partial pressure of oxygen dissolved in liquid. Foruse in a ventilation apparatus, however, a housing that isflowthrough-capable for the measured-object fluid is advantageous. It istherefore preferred that the housing comprise a further opening,different from the opening and located remotely therefrom, in such a waythat the housing is flowthrough-capable for fluid between the openingand the further opening.

It is thus possible in principle to arrange the reaction subassemblyadvantageously in a ventilation apparatus in the main ventilation gasflow. A preferably compact reaction subassembly can be obtained byproviding the layered component arrangement between the opening and thefurther opening.

The housing is preferably flowthrough-capable in a straight line, inorder to minimize eddying of the fluid to be detected as it passesthrough the housing and thus travels past the layered componentarrangement.

In order to implement the particularly advantageous application of thereaction subassembly under discussion here in a ventilation apparatus,provision is made according to an advantageous refinement of the presentinvention that the reaction subassembly is embodied for placement in aventilation conduit arrangement of a ventilation apparatus; the reactionsubassembly being embodied, in the region both of the opening and of thefurther opening, with a respective attachment configuration forconnection to a respective portion of the ventilation conduitarrangement.

Advantageously, the reaction subassembly is embodied as an oxygenmeasurement cuvette. A measurement cuvette of this kind as a rulecomprises at least one housing portion configured as a parallelepiped.The reaction subassembly is preferably arranged in such aparallelepipedal portion of the housing; a surface, preferably flat orcurved only around one axis of curvature, of the parallelepipedalportion of the housing preferably comprises both the reaction window andthe temperature detection window.

Because the reaction subassembly described above serves for sensorialdetection of the oxygen partial pressure and, derived therefrom, theoxygen content of a fluid, the present Application further relates to asensor arrangement encompassing a reaction subassembly as described andrefined above, and further encompassing a detector subassembly, having:

-   -   a radiation source that is embodied to emit the first        electromagnetic radiation through the reaction window;    -   a radiation detector that is embodied to detect the second        electromagnetic radiation through the reaction window; and    -   an infrared detector that is embodied to detect, through the        temperature-detection window, the infrared radiation emitted        from the temperature-detection laminate.

In order to minimize mutual radiation interference, the infrareddetector and the radiation source are preferably arranged in measurementspaces that are shielded from one another in terms of the firstelectromagnetic radiation and the infrared radiation.

Although what is envisioned in the context of utilization of the sensorarrangement is preferably utilization in a ventilation apparatus or ininteraction therewith, be it noted that the sensor arrangement isembodied in principle to detect any oxygen partial pressures of oxygendissolved in a fluid. The fluid is, however, preferably respiratory gas.

In order to allow a high level of component hygiene to be ensured in thecontext of the reaction subassembly that comes directly into contactwith the fluid, it is advantageous (as already mentioned above) if thedetector subassembly is connectable or connected detachably to thereaction subassembly. The substantially more expensive detectorsubassembly can thus be used, sequentially in time, with severalreaction subassemblies for the detection of oxygen contents in fluids.

The aforementioned reaction subassembly is therefore preferably asingle-use or disposable reaction subassembly that, for example inclinical use, can be disposed of after being used once on one patient.For maximally simple and definite, in particular unambiguous, detachableconnection of a reusable detector subassembly to the reactionsubassembly, in particular to the reaction subassembly embodied as anoxygen measurement cuvette, embodiment of the parallelepipedal portionas a cuboidal portion is preferred. Advantageously, the cuboidal portioncan comprise enveloping-side surface pairs of different widths, in orderto prevent incorrect attachment of the detector subassembly to thehousing, in particular to the measurement cuvette.

As explained earlier in connection with the layered componentarrangement, calibration of the noncontact infrared-based temperaturedetection of the temperature-detection laminate using the actualtemperature of the reaction laminate which is of interest can benecessary or at least advantageous in order to obtain a maximallyaccurate luminophore-based result from detection of the oxygen contentin the measured-object fluid. Provision can be made for this purposethat the sensor arrangement is signal-transferringly connected to anelectronic evaluation apparatus that comprises at least a data memoryand a data processing processor in data exchanging communication withthe data memory, calibration information for correlating detectedinfrared radiation of the temperature-detection laminate with thetemperature of the luminophore being stored in the data memory.

The temperature of the luminophore is equivalent to the temperature ofthe reaction laminate, the temperature of the detection side of thereaction laminate being of particular interest.

The calibration can be accomplished in advance, for the specific layeredcomponent arrangement or specific reaction subassembly or for a class oflaminates or reaction subassemblies, in the laboratory. For this, thetwo laminates can be brought successively to thermal equilibrium statesat temperatures that are each different but are uniform and known. Foreach equilibrium state, the detected value of the infrared radiationemitted from the temperature-detection laminate can then be associatedwith the respective known equilibrium temperature of the reactionlaminate.

In order to check that the temperature-detection laminate is tracking achange in the temperature of the reaction laminate sufficiently quickly,the two fluid-contact sides can be brought into contact with atemperature source having a known temperature that changes over time ina known manner, and the temperatures of the detection sides of the twolaminates can be detected in noncontact fashion as a function of time.

From the data thereby obtained, a highly accurate calibrationrelationship can be obtained between a temperature detected innoncontact fashion at the detection side of the temperature-detectionlaminate and the temperature of the detection side of the reactionlaminate, and thus the temperature of the luminophore present therein.

The electronic evaluation apparatus can furthermore contain calibrationinformation for correlating second electromagnetic radiation detected bythe radiation detector with an oxygen concentration value or oxygencontent value of the measured-object fluid. As discussed earlier, thesecond electromagnetic radiation detected by the radiation detector, orthat radiation's relationship to the exciting first electromagneticradiation in terms of time and/or intensity, correlates directly withthe partial pressure of the oxygen in the measured-object fluid. Theoxygen concentration or oxygen content of the fluid can nevertheless bereadily ascertained or calculated from the detected partial pressure.

Because the preferred application instance of the above-described sensorarrangement is interaction thereof with a ventilation apparatus forartificial ventilation, the present invention further relates to aventilation apparatus for artificial ventilation, having:

-   -   a respiratory gas source;    -   a ventilation conduit arrangement extending between the        respiratory gas source and a patient-side proximal end;    -   a valve arrangement encompassing an inhalation valve and an        exhalation valve;    -   a flowthrough sensor arrangement for quantitative detection of a        gas flow in the ventilation conduit arrangement;    -   a pressure modification arrangement for modifying the gas        pressure of the gas flowing in the ventilation conduit        arrangement; and having    -   a control device that is configured at least to control the        operation of the pressure modification arrangement on the basis        of measurement signals of the proximal flowthrough sensor; and    -   a sensor arrangement as presented above and advantageously        refined, for ascertaining an oxygen content of gas flowing in        the ventilation conduit arrangement.

A “respiratory gas source” is understood very generally to be any typeof respiratory gas source that serves to introduce respiratory gas intothe ventilation conduit arrangement. It can be an attachmentconfiguration of the ventilation apparatus which is embodied forconnection to a respiratory gas reservoir that is replaceable or isinstalled in permanent stationary fashion. It can also be a pump that,in the respiratory gas apparatus, aspirates gas from a reservoir (whichcan also be the external environment), and introduces it into theventilation conduit arrangement. A pump of this kind can also beconfigured as a fan.

A “pressure modification arrangement” is to be understood as anyapparatus that is suitable and intended for modifying the pressure ofthe respiratory gas flowing in the ventilation conduit arrangement. Whenthe respiratory gas source is merely an attachment configuration forconnection to a gas reservoir installed in stationary fashion, it can bea valve arrangement for pressure reduction. When the respiratory gassource comprises the aforementioned pump or fan, the pressuremodification arrangement can itself encompass, or can in fact be, partsor the entirety of the respiratory gas source, for example the pump orthe fan, whose output can be modified by the control device. Even whenthe respiratory gas source is constituted by the aforementioned pump orfan, the pressure modification arrangement, in addition to therespiratory gas source, can itself encompass a pressure reduction valveor can be constituted exclusively by a pressure reduction valve, forexample if the pump or fan runs at a constant load.

The control apparatus preferably encompasses the aforementionedelectronic evaluation apparatus of the sensor arrangement, or is thelatter apparatus.

The sensor arrangement is preferably arranged in the main respiratorygas flow, so that it can directly detect at least one flow from amongthe inhalatory and the exhalatory respiratory gas flow. The sensorarrangement is preferably provided in the ventilation conduitarrangement in such a way that it can detect both an exhalatory and aninhalatory respiratory gas flow. The sensor arrangement can be arrangedfor that purpose close to the patient, i.e. proximally, preferablybetween a Y connection with which separate exhalatory and inhalatoryventilation conduit portions are combined in a direction toward thepatient, and an endotracheal tube on the patient.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

Also preferably, the sensor arrangement is arranged between the point atwhich separate exhalatory and inhalatory ventilation conduit portionscombine in a direction toward the patient, and the flowthrough sensor.

The present invention will be explained in further detail below withreference to the appended drawings, in which:

FIG. 1 depicts a preferred but nonetheless merely exemplifyingapplication of the layered component arrangement, reaction subassembly,and sensor arrangement according to the present invention, in aventilation apparatus according to the present invention;

FIG. 2A is a schematic plan view of a planar layered componentarrangement according to the present invention of the presentapplication;

FIG. 2B is a section view through the layered component arrangement ofFIG. 2A, along section plane IIB-IIB of FIG. 2A;

FIG. 3A is a plan view of a subassembly encompassing the layeredcomponent arrangement of FIGS. 2A and 2B and a window component of ahousing, receiving the layered component arrangement, of a reactionsubassembly;

FIG. 3B is a section view through the subassembly of FIG. 3A, alongsection plane IIIB-IIIB of FIG. 3A;

FIG. 4 shows a reaction subassembly according to the present inventionof the present application, and

FIG. 5 is a schematic cross-sectional view through a sensor arrangementaccording to the present invention, having the reaction subassembly ofFIG. 4 , which is utilized as a sensor arrangement on the ventilationapparatus of FIG. 1 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In order to explain the preferred area of application of the subjectmatters discussed in the present Application (layered componentarrangement, reaction subassembly, sensor arrangement, and ventilationapparatus), a ventilation apparatus utilizing the aforesaid componentswill firstly be explained in conjunction with FIG. 1 .

In FIG. 1 , an embodiment according to the present invention of aventilation apparatus is labeled in general with the number 10. In theexample depicted, ventilation apparatus 10 serves for artificialventilation of a human patient 12.

Ventilation apparatus 10, constituting a mobile ventilation apparatus10, can be received on a rollable frame 13.

Ventilation apparatus 10 comprises a housing in which a pressuremodification apparatus 16 and a control device 18 (not visible fromoutside because of the opaque housing material) can be received.

Pressure modification arrangement 16 is constructed in a manner knownper se and comprises a respiratory gas source 15 in the form of a pump,a compressor, or a fan; these can each be controlled in modifiable-loadfashion and therefore serve not only to introduce respiratory gas intothe ventilation apparatus but also to modify the pressure of therespiratory gas that is introduced. Alternatively, respiratory gassource 15 can also be constituted by a pressure container that isattachable to housing 14 of ventilation apparatus 10. Pressuremodification arrangement 16 can comprise respiratory gas source 15 and,if applicable, additionally (or, in the case of a pressurized gasreservoir constituting a respiratory gas source, alternatively) areducing valve and the like. Ventilation apparatus 10 furthermorecomprises, in a manner known per se, an inhalation valve 20 and anexhalation valve 22.

Control device 18 is usually implemented as a computer ormicroprocessor. It encompasses a data memory device (not depicted inFIG. 1 ) so that data necessary for the operation of ventilationapparatus 10 can be stored and, if necessary, retrieved. In a networkoperation context, the memory device can also be located outside housing14 and can be connected to control device 18 via a data transferconnection. The data transfer connection can be constituted by a cablelink or a radio link. So that disruptions of the data transferconnection can be prevented from affecting the operation of ventilationapparatus 10, however, the memory device is preferably integrated intocontrol device 18 or is at least received in the same housing 14 as it.

For the input of data into ventilation apparatus 10, or more preciselyinto control device 18, ventilation apparatus 10 comprises a data input24 that is represented, in the example depicted in FIG. 1 , by a keypad.Alternatively or in addition to the keypad that is depicted, controldevice 18 can receive data via various data inputs, for example via anetwork lead, a radio link, or via sensor terminals 26 that will bediscussed in detail below.

Ventilation apparatus 10 can comprise an output device 28, in theexample depicted a display screen, in order to output data to thetherapist performing treatment.

For artificial ventilation, patient 12 is connected via a ventilationconduit arrangement 30 to ventilation apparatus 10, more precisely topressure modification arrangement 16 in housing 14. Patient 12 isintubated for this purpose with an endotracheal tube 58.

Ventilation conduit arrangement 30, through which fresh respiratory gascan be directed from respiratory gas source 15 and pressure modificationarrangement 16 into the lungs of patient 12, comprises an inhalationhose 32 outside housing 14. Inhalation hose 32 can be interrupted, andcan comprise a first partial inhalation hose 34 and a second partialinhalation hose 36 between which a conditioning device 38, forcontrolled humidification and optionally also temperature control of thefresh respiratory gas delivered to patient 12, can be provided.Conditioning device 38 can be connected to an external fluid reservoir40 by way of which water for humidification, or also a medication e.g.to inhibit inflammation or to dilate the airways, can be delivered tothe respiratory gas. When the present ventilation apparatus 10 is usedas an anesthesia ventilation apparatus, it is thereby possible todeliver volatile anesthetics in controlled fashion via ventilationapparatus 10 to patient 12. Conditioning device 38 ensures that thefresh respiratory gas is conveyed to patient 12 with a predeterminedmoisture content, optionally with addition of a medication aerosol, andat a predetermined temperature.

Ventilation conduit arrangement 30 comprises, in addition to inhalationvalve 20 already mentioned, exhalation valve 22 and furthermore anexhalation hose 42 through which metabolized respiratory gas from thelungs of patient 12 is exhausted into the atmosphere.

Inhalation hose 32 is coupled to inhalation valve 20, and exhalationhose 42 to exhalation valve 22. Only one of the two valves is open atone time for passage of a gas flow. Actuation control of valves 20 and22 is also effected by control device 18.

During a ventilation cycle, firstly exhalation valve 22 is closed andinhalation valve 20 is opened for the duration of the inhalation phase,so that fresh respiratory gas can be directed from housing 14 to patient12. A flow of fresh respiratory gas is produced by pressure modificationarrangement 16 by controlled elevation of the pressure of therespiratory gas. As a result of the pressure elevation, the freshrespiratory gas flows into the lungs of patient 12 where it expands thebody region in the vicinity of the lungs, i.e. in particular the thorax,against the individual elasticity of the body parts near the lungs. Thegas pressure in the interior of the lungs of patient 12 also rises as aresult.

At the end of the inhalation phase, inhalation valve 20 is closed andexhalation valve 22 is opened. The exhalation phase begins. Because thegas pressure of the respiratory gas present in the lungs of patient 12has been elevated until the end of the inhalation phase, said gas flowsinto the atmosphere after exhalation valve 22 is opened, while the gaspressure in the lungs of patient 12 decreases as the flow continues.When the gas pressure in lungs 12 reaches a positive final exhalationpressure that is set on ventilation apparatus 10, i.e. a pressureslightly higher than atmospheric pressure, the exhalation phase isterminated with the closing of exhalation valve 22, and is followed by afurther ventilation cycle.

During the inhalation phase, the so-called ventilation tidal volume,i.e. the volume of respiratory gas for each breath, is delivered topatient 12. The ventilation tidal volume multiplied by the number ofventilation cycles per minute, i.e. multiplied by the ventilationfrequency, equals the volume per minute of artificial ventilation beingperformed in the present case.

Ventilation apparatus 10, in particular control device 18, is preferablyembodied to repeatedly update or ascertain, during ventilationoperation, ventilation operating parameters that characterize theventilation operation of ventilation apparatus 10, in order to ensurethat ventilation operation is coordinated as optimally as possible, atevery point in time, with patient 12 who is respectively to beventilated. Particularly advantageously, the determination of one orseveral ventilation operation parameters is made at the ventilationfrequency, so that ventilation operating parameters that are current,and are thus optimally adapted to patient 12, can be furnished for eachventilation cycle.

Ventilation apparatus 10 is data-transferringly connected for thispurpose to one or several sensors that monitor the status of the patientand/or monitor operation of the ventilation apparatus.

One of these sensors is a proximal flow sensor 44 that is arranged atthat end of a Y-connector piece 45 which is located closer to patient12, and detects the ventilation gas flow existing at that point inventilation conduit arrangement 30. Flow sensor 44 can be coupled bymeans of a sensor lead arrangement 46 to data inputs 26 of controldevice 18. Sensor lead arrangement 46 can, but does not need to,encompass electrical signal transfer leads. It can likewise comprisehose conduits that transfer the gas pressure existing in a flowdirection on either side of flow sensor 44 to data inputs 26, where thatpressure is quantified by pressure sensors 27. Flow sensor 44 ispreferably a flow sensor operating on the differential pressureprinciple, but can also be a flow sensor operating in accordance with adifferent physical operating principle.

Provided in housing 14 is a further flow sensor 48 that is referred to,because of its greater distance from patient 12 compared with theproximal flow sensor 44, as a “distal” flow sensor 48.

A sensor arrangement 50, encompassing a reaction subassembly 72 having ahousing 52 embodied as a measurement cuvette 52 and a detectorsubassembly 54, is arranged in ventilation conduit arrangement 30between Y-connector piece 45 and flow sensor 44, in order to detect theoxygen content of the respiratory gas in both the exhalatory and theinhalatory main respiratory gas flow. Sensor arrangement 50, which willbe explained in further detail below in conjunction with FIG. 5 , iscoupled via a signal lead 56 to control device 18 and transfers to thelatter, for further evaluation, the detection results of its detectorsubassembly 54.

Calibration information is stored in the data memory device of controldevice 18 so that the detection results of sensor arrangement 50 can bevery accurately evaluated.

Sensor arrangement 50 is embodied for temperature-compensatedluminophore based detection of the partial pressure of the oxygencontained in the respiratory gas flowing through housing 52. Bothtemperature compensation, and conversion of the detection resultsobtained directly in conjunction with the oxygen partial pressure intoan oxygen concentration or oxygen content of the respiratory gas, areperformed by control device 18 based on the stored calibrationinformation.

Luminophore-based detection of an oxygen content in a fluid is known perse. In the present exemplifying embodiment it is accomplished with theparticipation of a layered component arrangement of the presentinvention which is depicted in FIGS. 2A and 2B and is labeled in generalwith the number 60. It encompasses, for optical detection of an oxygencontent of the measured-object fluid, such as that of the aforementionedrespiratory gas, a reaction laminate 62 (see also FIG. 2B), which in thepresent case is depicted as a two-ply reaction laminate 62. Reactionlaminate 62 can in fact comprise only one layer, or also more than twolayers. In the example depicted, and also as evident in thecross-sectional view of FIG. 2B, reaction laminate 62 comprises asubstrate ply 62 a and a luminophore-containing reaction layer 62 bapplied thereonto.

The relationships of the length and width of reaction laminate 62 to itsthickness are not to scale in the Figures. Reaction laminate 62,depicted in FIGS. 2A and 2B as square, can have an edge length ofapproximately 7 to 10 mm, and its thickness, measured over both layers62 a and 62 b, can be approximately 300 um.

Substrate ply 62 a can be constituted from a material that issufficiently porous with respect to oxygen molecules, for examplepolyvinylidene fluoride. Substrate ply 62 a can be cut out from acorresponding film and can have a thickness of between 100 and 150 um.In some circumstances the thickness of the substrate ply can also beless.

Luminophore-containing reaction layer 62 b can likewise containpolyvinylidene fluoride as a matrix material into which luminophores areembedded.

Reaction laminate 62 has a fluid-contact side 62 c and a detection side62 d.

Luminophore-containing reaction layer 62 b can be embodied to beslightly smaller than substrate ply 62 a that carries it, in order tosimplify adhesive mounting of reaction laminate 62 on the detection sideonto a window component or generally a housing, without therebyrequiring the detection side of luminophore-containing reaction layer 62b to be coated with adhesive.

As will be explained below in conjunction with FIG. 5 and as isgenerally known in principle, reaction layer 62 b is irradiated with afirst electromagnetic radiation of a first wavelength and is therebyexcited to emit a second electromagnetic radiation having a second, as arule longer, wavelength. The intensity and the duration of the excitedsecond electromagnetic radiation depend on the presence of oxygen, moreprecisely on contact between the luminophores embedded in reaction layer62 b and oxygen. The emission behavior of reaction layer 62 b isfurthermore temperature dependent.

For temperature compensation of the detection of the emission behaviorof reaction laminate 62, layered component arrangement 60 comprises atemperature-detection laminate that, in the example depicted, occupiesan area identical in size to that of reaction laminate 62, although thisis not obligatorily necessary.

The depiction of temperature-detection laminate 64 is also not to scalein terms of its dimensions. In the example depicted it has an edgelength in the same range as reaction laminate 62, but because itsconstruction differs from that of reaction laminate 62 it is preferablythinner than the latter.

Temperature-detection laminate 64 once again comprises a substrate ply64 a that, in the interest of optimum thermal conduction, is constitutedby way of example from an aluminum foil having a thickness ofapproximately 10 um or even less.

In the exemplifying embodiment depicted, a detection layer 64 b, forexample made of a carbon-containing paint, is applied onto substrate ply64 a. As indicated by way of example in the introductory part of thespecification, the carbon-containing paint encompasses carbon as a blackcolor pigment and therefore has a very high emissivity of more than 0.9.

Because, as will be explained below in conjunction with FIGS. 3A and 3B,the infrared radiation proceeding from detection layer 64 b is detectedthrough a, for example circular, hole 68 that has a constantly circularcross section along its hole axis along which hole 68 extends, detectionlayer 64 b is also embodied as a circular surface on substrate ply 64 athat is, for example, of square configuration.

That surface of substrate ply 64 a which faces away from detection layer64 b is exposed, constituting a fluid-contact side 64 c. It isconstituted by the metallic surface of the aluminum foil which formssubstrate ply 64 a of temperature-detection laminate 64. Detection side64 d of temperature-detection laminate 64 constitutes the exposedsurface of detection layer 64 b. Fluid can therefore flow past layeredcomponent arrangement 60 on its fluid-contact side 620, 64 c; oxygentravels through substrate ply 62 a to luminophore-containing reactionlayer 62 b where it causes quenching of an excitation generated by thefirst electromagnetic radiation, while the fluid contact onfluid-contact side 64 c of temperature-detection laminate 64 serves onlyto transfer heat from the fluid to temperature-detection laminate 64.

Because of the material (aluminum) selected for substrate ply 64 a, andbecause it is thin, substrate ply 64 a assumes within milliseconds thetemperature of the fluid flowing past it on its fluid-contact side 64 c,and also ensures temperature equalization of detection layer 64 b, sothat a temperature value that is at least correlated with thetemperature of the measured-object fluid can be detected by an infrareddetector on detection side 64 d of temperature-detection laminate 64.Because reaction laminate 62 comes into contact with the same fluid inapproximately the same manner, detection of the temperature of detectionside 64 d of temperature-detection laminate 64 makes possible, based onthe calibration information stored in the data memory device of controldevice 18, inferences as to the temperature of detection side 62 d ofreaction layer 62 b, this being a prerequisite for temperaturecompensation of the measurement results obtained at reaction laminate 62regarding the oxygen content of the measured-object fluid.

Temperature compensation is necessary because the temperature of themeasured object fluid can change as it flows past layered componentarrangement 60, for example because in the ventilation apparatus of FIG.1 , the temperature of the ventilation air delivered to a patient islower than when it is returned by exhalation after breathing out.

Layered component arrangement 60 is therefore usually arranged inhousing 52 which guides the flow of the measured-object fluid while itsoxygen content, and the temperature, are being detected.

Detection sides 62 d and 64 d of the two laminates 62 and 64 areadvantageously directed outward, i.e. away from the measured-objectfluid, while fluid-contact sides 620, 64 c of the two laminates comeinto contact with the fluid over the largest possible area.

In order to ensure that only oxygen dissolved in the measured-objectfluid reaches reaction layer 62 b, the reaction laminate is covered onits detection side by a window. FIG. 3A shows layered componentarrangement 60 of FIGS. 2A and 2B in the plan view of FIG. 2A, with awindow component 66 arranged thereabove. Window component 66 is part ofhousing 52, shown in FIG. 1 , of sensor arrangement 50. The windowcomponent can be constituted from a transparent polyamide, or also fromanother plastic that is transparent to the first and the secondelectromagnetic radiation. Window component 66 can be constituted, forexample, from the amorphous polyamide that is offered under the name“Grilamid TR” by EMS-Chemie AG in Domat (CH).

In its region located directly above reaction layer 62 b, windowcomponent 66 thus forms a reaction window 66 a through which the firstelectromagnetic radiation reaches reaction layer 62 b, and through whichthe emitted second electromagnetic radiation, excited thereby, istransmitted.

In order to allow the infrared radiation emitted from detection layer 64b of temperature-detection laminate 64 to be detected with minimaldistortion, there is embodied in window component 66, directly above thelocation at which the temperature-detection laminate is arranged, adetection window 66 b which is embodied as a hole 68 that widens innegatively conical fashion from the side facing away from layeredcomponent arrangement 60 to detection layer 64 b, and that passesthrough the entire thickness of window component 66.

The circular hole edge 68 a on that side of window component 66 whichfaces toward detection layer 64 b is larger in diameter than theconcentric hole edge 68 b of hole 68 on that side of window component 66which faces away from detection layer 64 b. The negatively conical holewall 68 c extending between the two hole edges 68 a and 68 b ispreferably coated, particularly preferably mirror-coated, in order tominimize or rule out interference from radiation components that mightbe guided through window component 66.

FIG. 4 depicts housing 52 of sensor arrangement 50 in a kind of explodedview.

Housing 52 encompasses a base housing 53 and window component 66 havinglayered component arrangement 60 that is arranged therein but is notvisible in FIG. 4 . An opening 70 in base housing 53 can be closed offwith window component 66, so that housing 52 is then sealed and, becauseof the arrangement of layered component arrangement 60 therein, formsreaction subassembly 72.

Housing 52 comprises, on both sides of parallelepipedal portion 74 thatis constituted with the participation of window component 66, attachmentfittings 76 a and 76 b for the attachment thereonto of ventilationconduit portions.

Housing 52 is flowthrough-capable bidirectionally along flow axis S.

FIG. 5 schematically depicts sensor arrangement 50 in cross section.

Respiratory gas can flow through housing 52 bidirectionally, between itstwo openings 78 a and 78 b, along flow axis S. The respiratory gascontacts fluid-contact sides 62 c and 64 c of laminates 62 and 64 as itflows past them. Flow axis S lies in the drawing plane of FIG. 5 .

Sensor arrangement 54, which can be arranged detachably on housing 52and which for that purpose surrounds parallelepipedal portion 74 inU-shaped fashion on three sides, the base of the “U” being locatedopposite window component 66, encompasses two measurement chambers 80and 82 that are physically separate from one another.

Provided in measurement chamber 80 is a radiation source 82, for examplein the form of an LED, which emits electromagnetic radiation E1 of afirst wavelength. In order to keep the wavelength band of the firstelectromagnetic radiation proceeding from radiation source 82 as narrowas possible, and to avoid spurious radiation, radiation source 82 canadvantageously be surrounded by a filter body 84 that allows firstelectromagnetic radiation E1, having the aforesaid wavelength, to passwith the narrowest possible tolerance.

Also arranged in first measurement chamber 80 is a radiation detector 86that detects a second electromagnetic radiation E2 which proceeds fromreaction layer 62 b after the latter is excited by first electromagneticradiation E1. Radiation detector 86 can also have a radiation filter 88in front of it in order to allow the passage only of secondelectromagnetic radiation E2, having its second wavelength that isdifferent from the first wavelength. With filter arrangements 84 and 88it is possible to ensure that no radiation travels directly fromradiation source 82 to radiation detector 88, creating “noise” in thesignal detected there.

The signal outputted by radiation detector 86 as a result of itsdetection of second electromagnetic radiation E2 is transferred via datalead 56 (shown in FIG. 1 ) to control device 18. It is indicative, in amanner known per se, of the oxygen partial pressure in the fluid flowingthrough housing 52.

An infrared detector 90, which detects infrared radiation I emitted fromdetection layer 64 b, is arranged in second measurement chamber 82. Thesignal outputted from infrared detector 90 as a result of its detectionof infrared radiation I is also transferred via data lead 56 to controldevice 18. This signal is indicative of a temperature of detection layer64 b.

Based on the calibration information that is stored in the data memorydevice of control device 18 and was ascertained remotely in thelaboratory before the deployment of layered component arrangement 60,control device 18 can ascertain from the detected signal of infrareddetector 90 the temperature of reaction layer 62 b for each point intime at which a signal of radiation detector 86 is detected, and canthereby compensate the detected signal of radiation detector 86 withreference to the temperature of the emitting reaction laminate 62 or ofreaction layer 62 b thereof. The result is a highly accuratedetermination of the oxygen partial pressure in the fluid flow throughhousing 52, as a value varying over time.

Highly accurate temperature compensation is achieved here with extremelysimple means, for example metal foil 64 a as a substrate and detectionlayer 64 b applied thereonto. The use of metal foil 64 a (aluminum foil)makes it possible to penetrate completely through window component 66,or housing 52 in general, in order to constitute a detection window 68,so that temperature information emitted as infrared radiation fromdetection layer 64 b reaches infrared detector 90 with as littledistortion as possible.

Control device 18 can contain, in a data memory, further calibrationinformation that makes possible the usual conversion of the oxygenpartial pressure of the fluid, which is directly correlated with thedetection of the second electromagnetic radiation, into an oxygencontent of said fluid.

The invention claimed is:
 1. A reaction subassembly, comprising ahousing and a layered component arrangement for temperature-compensatedoptical detection of an oxygen content of a fluid, which is provided inthe housing, said layered component arrangement comprising aluminophore-containing reaction laminate having a luminophore that isexcitable by irradiation with a first electromagnetic radiation of afirst wavelength, to emit a second electromagnetic radiation of a secondwavelength different than the first wavelength, the excited emissionbehavior of the luminophore being dependent on an oxygen partialpressure in a fluid contacting the luminophore, and atemperature-detection laminate emitting an infrared radiation, whereinthe reaction laminate and the temperature-detection laminate areembodied separately from one another; the housing comprising: an openingthrough which a fluid is introducible into the housing; a reactionwindow through which the reaction laminate is reachable by the firstelectromagnetic radiation and which is penetrable by the secondelectromagnetic radiation; and a temperature-sensing window, arrangedphysically remotely from the reaction window, which is penetrable by theinfrared radiation emitted from the temperature-detection laminate. 2.The reaction subassembly according to claim 1, wherein the reactionwindow is configured physically differently from thetemperature-detection window.
 3. The reaction subassembly according toclaim 2, wherein the reaction window is thicker than thetemperature-detection window.
 4. The reaction subassembly according toclaim 3, wherein the reaction window comprises a material that istransparent to light in the optically perceptible wavelength region; andthe temperature-detection window encompasses a hole that passes throughthe housing and is covered by the temperature-detection laminate.
 5. Thereaction subassembly according to claim 1, wherein the housing comprisesa further opening, different from the opening and located remotelytherefrom, in such a way that the housing is flowthrough-capable forfluid between the opening and the further opening.
 6. The reactionsubassembly according to claim 5, wherein the layered componentarrangement is provided between the opening and the further opening. 7.The reaction subassembly according to claim 5, wherein the subassemblyis adapted for placement in a ventilation conduit arrangement of aventilation apparatus; the reaction subassembly is adapted, in theregion both of the opening and of the further opening, with a respectiveattachment configuration for connection to a respective portion of theventilation conduit arrangement.
 8. A sensor arrangement encompassingcomprising a reaction subassembly according to claim 1 and furthercomprising a detector subassembly comprising: a radiation source that isadapted to emit the first electromagnetic radiation through the reactionwindow; a radiation detector that is adapted to detect the secondelectromagnetic radiation through the reaction window; and an infrareddetector that is adapted to detect, through the temperature-detectionwindow, the infrared radiation emitted from the temperature-detectionlaminate.
 9. The sensor arrangement according to claim 8, wherein thedetector subassembly is connectable or connected detachably to thereaction subassembly.
 10. The sensor arrangement according to claim 8,wherein said sensor arrangement is signal-transferringly connected to anelectronic evaluation apparatus that comprises at least a data memoryand a data processing processor in data-exchanging communication withthe data memory, calibration information for correlating detectedinfrared radiation of the temperature-detection laminate with thetemperature of the luminophore being stored in the data memory.
 11. Aventilation apparatus for artificial ventilation, having: a respiratorygas source; a ventilation conduit arrangement extending between therespiratory gas source and a patient-side proximal end; a valvearrangement encompassing an inhalation valve and an exhalation valve; aflowthrough sensor arrangement for quantitative detection of a gas flowin the ventilation conduit arrangement; a pressure modificationarrangement for modifying the gas pressure of the gas flowing in theventilation conduit arrangement; and having a control device that isconfigured at least to control the operation of the pressuremodification arrangement on the basis of measurement signals of theproximal flowthrough sensor; and a sensor arrangement according to oneof claim 8, for ascertaining an oxygen content of gas flowing in theventilation conduit arrangement.
 12. The reaction subassembly accordingto claim 7, wherein the subassembly is adapted as an oxygen measurementcuvette.